The present invention relates to reduction of power consumption of a portable communication terminal such as a portable telephone or the like.
A conventional portable telephone includes a communication control processor and a data processing control processor for controlling a man-machine interface such as a keypad, a liquid crystal display and the like. FIG. 1 shows an internal configuration of a conventional portable telephone 100.
Receiving operation of the conventional portable telephone will be described with reference to FIG. 1. A digital baseband unit 104 converts a signal received by an RF (Radio Frequency) unit 102 into a baseband signal. A communication control processor 110 processes the baseband signal. Depending on contents of the baseband signal, the communication control processor 110 transmits data to a data processing control processor 120. The data processing control processor 120 receives the data from the communication control processor 110, and outputs data to be displayed on a display unit 108 (for example a liquid crystal display).
Transmitting operation of the conventional portable telephone will be described. First, the data processing control processor 120 receives a user input from an operating unit 106 (for example a keypad). Depending on contents of the user input, the data processing control processor 120 transmits data to the communication control processor 110. The communication control processor 110 receives the data from the data processing control processor 120, and transmits the data via the digital baseband unit 104 and the RF unit 102.
Thus, the communication control processor 110 and the data processing control processor 120 perform therebetween communication and data processing (to display data on the display unit 108 and transmit data via the digital baseband unit 104 and the like). In order to allow such communication and data processing, power and clocks of both the communication control processor 110 and the data processing control processor 120 are turned on. Hence, not only a setup signal line 131 for data transmission and reception and a signal line 132 for data transmission and reception but also signal lines 134a and 134b for communicating a state (whether the clock is on) of each of the communication control processor 110 and the data processing control processor 120 to the other and interrupt signal lines 136a and 136b for each of the communication control processor 110 and the data processing control processor 120 to turn on the clock of the other are provided between the communication control processor 110 and the data processing control processor 120.
For example, in a case of an incoming call, the communication control processor 110 may perform communication and data processing with the data processing control processor 120. Thus, the communication control processor 110 grasps the state of the data processing control processor 120 through the signal line 134b, and when the data processing control processor 120 is in a sleep state, the communication control processor 110 turns on the clock of the data processing control processor 120 through the signal line 136a. Incidentally, the communication control processor 110 may not perform communication and data processing with the data processing control processor 120. However, when the clock of the data processing control processor 120 is not turned on and a need arises for communication and data processing with the data processing control processor 120, the need cannot be met. Therefore, each time there is an incoming call, the communication control processor 110 needs to perform the processing of grasping the state of the data processing control processor 120 and turning on the clock of the processor 120.
However, when one of the clocks of the communication control processor 110 and the data processing control processor 120 is turned on with an incoming call or the like, the other of the clocks of the communication control processor 110 and the data processing control processor 120 needs to be turned on, thus resulting in too much power consumption by the communication control processor 110 and the data processing control processor 120.